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-rw-r--r--src/common/bswap.h15
1 files changed, 12 insertions, 3 deletions
diff --git a/src/common/bswap.h b/src/common/bswap.h
index 8f82a8f4..f5cb8345 100644
--- a/src/common/bswap.h
+++ b/src/common/bswap.h
@@ -16,20 +16,29 @@
// NOTE: We assume that config.h is already #included.
-// byteswap.h is a GNU extension. It contains inline assembly versions
-// for byteswapping. When byteswap.h is not available, we use generic code.
+// At least glibc has byteswap.h which contains inline assembly code for
+// byteswapping. Some systems have byteswap.h but lack one or more of the
+// bswap_xx macros/functions, which is why we check them separately even
+// if byteswap.h is available.
+
#ifdef HAVE_BYTESWAP_H
# include <byteswap.h>
-#else
+#endif
+
+#ifndef HAVE_BSWAP_16
# define bswap_16(num) \
(((num) << 8) | ((num) >> 8))
+#endif
+#ifndef HAVE_BSWAP_32
# define bswap_32(num) \
( (((num) << 24) ) \
| (((num) << 8) & UINT32_C(0x00FF0000)) \
| (((num) >> 8) & UINT32_C(0x0000FF00)) \
| (((num) >> 24) ) )
+#endif
+#ifndef HAVE_BSWAP_64
# define bswap_64(num) \
( (((num) << 56) ) \
| (((num) << 40) & UINT64_C(0x00FF000000000000)) \